Protractor drawing instrument



un 1927. 1 633 903 J e 28" F. N. PERRIN PROTRACTOR DRAWING INSTRUMENT Filed March 265 1926 a/ 5 QL 2 7 l f f 2:"\

26 z \3 \/4 Ej.' 25 /3 4 5 l l I f `lllllffmlml 4L l Ej. 3 3 f /2 4 INVENToR.

Patented June 28, 19.27. l l" UMEDSTAIES lrrto'rniioriioiaaaniiiivineINsninvigiir'r.l

l* .Appiication'" fii'ediiviarch 26,1926.; jsey'iaiit. 97,547.

i The object of my invention is tofzprovide a combination drawing tool that will readilyadapt itself to the several requireineiitsfof fundamental drafting.l 1 -v 5 Another object is to .combine a protractor and scale, iii such a `manner-and by jsuch means, so as to make it a convertible tool4 rangement of parts more fully hereinafter set forth. ,i

by. similar numerals.A 1

Fig-1 is: a 'plan viewof'my deviceshow. ing the general arrangement and combina-2v tion ofparts.

member. 1

. Fig, 31dean alternate-form of Ythe .PLTOQV tractor member,- showing the center portion; to `the 'r'orinati'on..offv

J thereof converted in natural vcurves.`

i It will nowfdescribefmorei-fullylthedel tailed :constructioiif of. my device, referring toftliedrawingsgand tlie..marks thereon. I,

perimeter, protractors. 4

scale may be placed in any desiredlposition on the protractorgmember.. and'` fixedly attached theretozby, apointedfsliding pivot:

The` scale being sof desigiiedvand arranged as to operateas a triangle or compass.

The protractor` frame .-1- issemi-circui-4 lar in form,liaving .'oiithe ,diameter`v thereof a straight edge 1l-. graduatedin even'` inches. Theprotractci- -lframe-is preferably made of thin celluloid sheet, 'having degree graduatioiis;-2-'-. along the under sideof the frame around the circumference thereof,

as is the `common practice ytor prcitractor-finstruments. A seriesofminerals.shown at -and -lextending around the perim- A'furtlierobject is'to producea drawingv manufactured at'V a very lovvy Y Similar parts-.on all'drawings are.ina'rked1 Fig/2 isA an edgevie'wfef thedevice shew-v f ing the relative` position of` the. prbtractor. member tothe scale; and the r connecting- In general my-.device comprises a pro-- tractor member, fully graduated aroundthein degreesas ordinarily vused on. '.Tliemember being provided; with slotted means for att-aching thereto,a` slotted scale, .and iii such a manner that thev eter "indicate the'iiumb'er :of degrees regis teredthereon fromfzero to one hundred and eiglityfdegrees, and numbering iii both ldire'ctionssonxthe' protractorscale. It is known,- liowever, that the .above method of indicat-.

ing degreesforpprotractors is 01d andin commoniise, but merelyenumerate-same t0y more lclearly illustrate their application in.

special combination and the operation of my device. *The center portion of tithe frame mle'inaybe cut out in a "semi-circm lar form' asiiidic'ated zby the Vcurved line -j5 and tlief'straight line -eG-of Fig."1-,.` orf it'lmay be formed AWith'irregular shaped illustratedin the-Fig, 3, providing a series" ofirregu'ljar curve'si used. inV drawing and 'def off'the protrac'tor` frame -"-1, is formed a narrow .slottedirecess ,--1'2-,1v positioned paral-lel VtetlieV'edgeZ-ll-y of fthe frame, and extendindnearly f across theY 'frame' member. Also in tliewed-ge -fl'lf-'q' atA theI center 'point ofthe prctr'ractor'frame is formed ay `Vesliapfed notch indicating the exact centeivof the` protractor 'circle' andthe degrees registeredtliereon; Thetedge '1l-"0f tl'iek fraineis' graduated in inches 'and fractions of inches, iasY indicated-by the marks 117- acrosstlieentire diameter of the circle, and bear-ingz'lines of #figures Aand ,-120* thereon for! indicating the number of inches registered, the same'bein'g numbered in both directioiis,tlieflengtli' of the Adiameter line bei'iigfmade iiifevenfiill inches. `Pivotally attached tothe rotracto'r'frame slot -12-' is atliin vslottec scale I lmember Y +14-, also oftransparentinaterial, and' is providedv with'anarrfow slotted-recess Silealong its centerline, nearly' the entire' length thereof. The scalev -is providedv with an .indicating arrow pointt16`fat one end, positioned on tliecenter lineof the scale, also both edges -of'the scale are graduated into inches and fractionsy of Vinches by the fine lines l -'flS-f; cut; thereon, and` in the samemanner as the :scale graduations +17- on v'the protractoredge-y lThe gradations .-18-v along botliedges of-'the scale. mem-1 bei"fflgareimarkedfwith lines of numbers -21- indicating the inch vmarks thereon, butfbeginningwith next'to the last number used on'tlieprotractorfframe in lines and *20-@fand continuing the numberingY` to the eiid ofthe scale", the lowernumber one,

the scale .being placed lat 'the arrowV l isprovided with a washer Q4- and operating nut -25-- The nut -25- being threaded to the pivot body and provides means for firmly attaching the scale -14- to the protractor frame 1- in any desired position;` The pivot member m9.2- is formed with a iattened Is-ection -26- for engaging the slot walls -12- and preventingl the pivot from turning therein, as the nut is tightened thereon; Upon loosening Vthe nut -25-, the scale .-lil-l may be moved to any position on thel protractor frame and `firmly clamped thereto. Both slots`-12 and 15; are so arranged and positioned that when the pivot wQ2-- is moved to the eXtreme end of the slot -12- of the protractor frame, indicated at the point -A- in Fig. 1, the scale -14- moved thereon to the extreme end of its slotted recess 15` on the arrow end of said of Fig. 1, the numbers on both the gradua-A tions- 17; and ,-18* will read successive and continuously from zero to the end of the sca-le, the scale 14ebeing adapted to operate from either side of the protractor frame -1-, the'lower edge of theprotractor frame and-the scale member 'lllforming a continuous straight linewhen the scale is extended'thereon. At the end of thescale `--14l--,y opposite to the arrow :end of-thel scale, isv formed a small hole -28-, designed forengaging a pencil point Ytherein for describing circles about the pivot -22-,

l as the sharp pivot point -23- engagesad- A:jacent supporting materiahas when placed AUO on a sheet of paper,an.d the point 28- pressed therein, converting the instrument into a. compass. The diameter of the circle Ydescribed may be varied by sliding the scale.l under the connecting pivot center #-22- before tightening the nut -25- thereon. For forming a triangle of any desired angle, the scale `14 is adjusted over the protractor frame 451.-, lacing the arrow point -16- o ver the grac uated degree mark along the circumference of the protractor circle, and placing the centerline of the scale slot 15M over the center point -13- of the protractor frame. The pivot 2Q- being adjusted in both slots l2- and -15- at their intersections, vand tightened by the nut +25-, holding the scale "14e-f inanv desired angle. The lower edge ofv the protractor frame may then be used as one edge of the triangle and the. angularly positioned scale `forming the other edge ot said triangle, the pivot point -23- at all times acting tohold the instrument in a positive position, or provide a positive center therefor.

Havingx'fully described .my protractor drawing instrument, what I claim as my iiivention and desire to secure by Letters Patent is;v Y Y 1. A drawing Vinstrument comprising a semi-circular shaped protractor frame with one straight side positioned along the diameter line of the protractor circle, a slotted recess formed near the straight side of the frame, said slot being positioned parallel to the straight side of said frame andextended nearly the entire Width thereof,'a thin scale member, havinga slotted recess nearly the entire length thereof, attached vto the pro'- tractor frame by a central pivot'engaging the slots ofboth the scale and protractor,

said pivot provided with means for locking the said scale in any desired position on the protractor frame, also having a sharp engaging point projecting from the bottomV side of the pivot for engaging a supporting sheet to establish al center point thereon, and the scale being provided with a pencil hole in one end' thereof for describing circles about'said centerpoint. 1

2. A drawing instrument comprising a combination ofc-'a semi-circular shaped protractor frame, same being one half of a cir cular disc cut on a diameter line,'and having a straight slotted recess formed near the-diameter line and parallel thereto, said'slotextending nearly the entire width ofthefprotractor frame, the circular section of said frame being graduated in degree, and the straight side ofthe frame being graduated into inches and fractions thereoffa thin straight scale member, graduated in inches along both edges thereof and provided with a narrow slot-ted recess along its center line for nearly its entire length, mounted on saidV protractor frame by means of a common pivot engaging both of the slotted recesses, said pivot having means for firmly clamping the frame and scale together in any desired position, and also provided with a sharp projecting point onthe bottom side of the pivot, said scale being provided with a small hole in one end thereof for engaging and receiving the point of a pencil forV describing circles about the pivot point'when the point is engaged plane surface. Y

3. A drawing instrument comprising a semi-circular shaped protractor frame made of thin transparent material. ysaid frame being one half of a circular disc and of even inches in diameter. graduation marks Vin degrees formed on the under side of the disc protractor frame about the circumference' therein, a flat scale member, having a slotted recess formed along its center line for nearly the entire length thereof, fitted over said pivot through its slotted recess, said scale member being provided with graduationl marks along both edges thereof indicating inches and fractions thereof, means for clamping said scale on the protractor frame in any desired position, and said scale being provided with a small pencil hole in one end thereof for describing a circle about the pointed pivot member therein.

4. A drawing instrument comprising av semi-circular shaped protractor, graduated in degrees around the circular section of its perimeter, and graduated in inches and fractions of inches along the straight side of said frame, said protractor being exactly one half of a circular disc cut on a diameter line, a

straight slotted recess formed through said frame near its straight edge and parallel thereto, said slot extending nearly across the frame, a sharp pointed pivot member engaging said slot and sli'dable therein, a thin scale member bearing graduation marks along both edges thereof indicating inches and fraction of inches, and having a slot formed along its center line, engaging said pivot through the scale slot, means attached to said pivot for clamping said scale to the protractor frame in any desired position, said slots being so arranged and limited that when the scale is extended to draw the pivot into the extreme ends of both slots, said scale being in an alignment with the straight edge of the protractor'frame, the inch graduation marks of both protractor andscale will coincide, and the numbers indicating the inches will read consecutively, said scale being provided with an indicating arrow at one end and with a small hole at the opposite end thereof, the hole being positioned on one of the inch graduation marks.

In witness whereof I sign these specifications.

FRANK N. PERRIN. 

